JPS6039859Y2 - variable size copying device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable magnification copying apparatus equipped with an optical device capable of converting the imaging magnification.

In a copying machine, the light irradiation position for the original and the exposure position for forming an image of the original on the photoreceptor are fixed, and the optical device that guides the irradiation light from the original to the photoreceptor is a lens for the purpose of downsizing the copying apparatus. It uses a mirror and a complex optical path that is reflected multiple times.

The more complicated the optical path becomes, the more complicated the magnification conversion device becomes.

SUMMARY OF THE INVENTION An object of the present invention is to provide a copying apparatus capable of converting magnification, which is equipped with an optical device having a simple structure that can easily change magnification in an optical device having a complicated optical path.

The principle and embodiments of the present invention will be explained based on the drawings.

In FIG. 1, when an object, for example, a document surface 1, is imaged by a lens A having a focal length f on an image forming surface, for example, a photoreceptor 1', a=b=2f when copying at the same magnification.

In this case, a is the distance between the subject 1 and the lens A, b is the distance between the lens A and the imaged image, and 1+1=earth bf.

Considering the positional relationship of the above-mentioned same-magnification imaging as a reference, the change in position at the time of magnification conversion will be considered.

If the lens A is moved by Δa to the position shown by the dashed-dotted line, and the distance from the lens to the imaging plane 1'' at that time is i + △b, then 1 1 - 10,000 + △a + i + △bf i + △b Magnification m =2f+6゜Δa=(Sat-1) f Δb=(m-1)f The displacement ΔL from the same magnification image plane position to the image plane 1″ is ΔL=
Δa+Δb=(m+L-2)f.

Here, Δa, Δb, and ΔL are each a. b, represents the amount of increase in L.

A slit exposure apparatus often uses a light beam whose principal ray does not coincide with the optical axis of the lens.

That is, oblique light rays tilted by a certain angle θ with respect to the optical axis are often used.

The distances corresponding to the distances Δa, Δb, and ΔL between the subject, lens, and imaging plane when using oblique rays are Δa′, △b′,
If △L', then △a'=△a/CO8θo=(±-1)f/CO3θ.

△b'=△b/cosθo: (m-1)f/cosθ
0△L'=△, [,/CO3θo=(m+±-2)f/
CO8θ.

Therefore, the direction of movement of each part is the direction of the chief ray inclined at an angle θ with respect to the optical axis, as shown in FIG.

When converting the imaging magnification, (a) fix the subject position and adjust the lens to Δa (or Δa').
), and the overall path between the subject position and the imaging plane changes by ΔL (or ΔL') due to movement of the imaging plane or movement of a mirror placed between the imaging plane and the lens. (b) Fix the lens and move the distance between the subject and the lens by △a (or △a') by moving the subject position or moving a mirror etc. placed between the subject position and the lens, and moving the distance between the image forming surface and the image forming surface by △b (or △b') by moving the image forming surface or moving a mirror placed between the image forming surface and the lens. Fix the image plane and move the lens to change the distance between the lens and the image plane by △b (or Δb'). There are three methods: changing the distance between the subject position and the lens by movement, and changing the entire path from the subject position to the imaging plane by ΔL (or ΔL').

In order to simplify the structure of a copying apparatus, it is required to fix the position of the subject and the image plane.

Therefore, the magnification conversion method is (a) above. (B)
, (c), it is preferable to move a mirror placed in the middle without moving the subject position or the imaging plane.

The relationship between the amount of movement when moving each part during magnification conversion is f・△b f・△a Δa=- or △”” xa+f △b+f ΔL=0□t or ΔL= (-hb )”△a+f
△b ten f When moving along the chief ray inclined to the optical axis,
f・△b'f・△a'△3=xb'
+f or △b' = lsa・or fΔL' = 0 sheep L
Or, △L'=Warbug Z △a+f △b'+f.

Therefore, by moving each part of the optical device so as to satisfy the above relationship, the magnification can be changed freely and reliably, and a clear image can be obtained on the imaging plane.

In the case of full-size copying, a copying device uses the set of copy paper as its traveling direction-side edge reference, and copies sets of originals of different sizes by aligning them with the side edge reference position in the document scanning direction. I can do it.

However, when performing variable magnification copying, the size of the image relative to the original changes with the center of the lens as the axis of symmetry, so if the original is set with the side edges as a reference, the setting position of the copy paper must be changed depending on the magnification. Must be.

By setting the original with the center of the lens and the position of the copy paper with the center of the lens, there is no change in the copy paper setting position due to the magnification, but the disadvantage is that setting the original becomes very cumbersome. have.

Therefore, it is preferable to adopt a method in which the original is set with the side edge as a reference, and the setting position of the copy paper does not change regardless of the conversion of the magnification.

Also, by doing this, the one side edge of the transfer paper will be at a constant position regardless of the size of the transfer paper, so you can choose a separation method that uses the first side edge of the transfer paper to separate the transfer paper from the photoreceptor. The degree of freedom in selecting a separation method increases.

In order to satisfy this requirement, it is necessary to shift the position of the optical axis or chief ray with respect to the imaging plane during magnification conversion.

That is, when converting magnification, it is necessary to move each part such as a lens in the direction of the optical axis or principal ray, and also in a direction intersecting the direction of the optical axis or principal ray.

In FIG. 3, which is a top view of the optical system in FIG. 1 or 2, the lens A is moved by Δa in the direction of the optical axis X and simultaneously moved by y in the direction Y perpendicular to the optical axis.

In this case, if the maximum copy width is W, -y Soba-=m (magnification) 2+y -mw Therefore, y=1+□・2 The relationship between y and Δa is △a W y=6°+2f”2 becomes.

When the lens is moved in a direction tilted at an angle θ to the optical axis, △a’cosθ W y: △a′CO3θ+2f”2 becomes.

In accordance with the above principle, by moving the lens in the direction of the optical axis or chief ray and in the direction crossing it, and by appropriately moving the necessary parts of the optical device such as mirrors, it is possible to change the copying magnification. An embodiment of a copying device capable of converting magnification according to the present invention, which improves operability as a reference and also uses the set of copy paper as a side edge reference, increases the degree of freedom in selecting a transfer paper separation method from a photoreceptor. explain.

If the illumination distribution of the original or the aperture near the imaging plane is not uniform in the Y direction during full-size copying, use the one-sided reference magnification that aligns the original set with the reference position on one side rather than the center of the lens as described above. If the conversion is performed, the balance of light quantity on the imaging plane may be disrupted and exposure unevenness that exceeds the permissible value may occur, so it is necessary to take measures for correcting the light quantity.

In FIG. 4, a contact glass 2 serving as a document support device is fixedly held on a machine frame 3 at a first document placement station 1 so that a book document can be placed thereon.

The second document placement station 4 is provided with a document table 5, a pair of document feed rollers 6 as a document support device, and a second contact glass 27.

An optical device 8 that projects light onto an original to form an image on a photoreceptor, such as a photosensitive drum 7, includes a light source 9 and a reflection device 10 that reflects light from the light source to form a slit irradiation on the original. A device, a first mirror 12 and a second mirror 13 that guide the reflected light from the original to the lens 11, and the light transmitted through the through lens 11 to the exposure position 1 of the photosensitive drum 7.
A third mirror 15 and a fourth mirror 16 are provided.

The photosensitive drum 7 is charged by a charger 17 by a commonly used means, an electrostatic latent image is formed by exposure at an exposure position 14, developed by a developing device 18, transferred to copy paper at a transfer position 19, and then transferred to a static eliminator. 20
The static electricity is removed by the cleaning device 21, and the same operation is repeated thereafter.

The copy paper supplied from the container 22 is transferred to the photosensitive drum 7 at the transfer position 19, and then sent to the fixing device 24 by the feeding device 23.

The copy paper fixed by the fixing device 24 is transferred to the feed roller 25.
is sent to the coheat tray 26.

The light source 9, the reflection device 10, and the first mirror 12 of the optical device are supported on a common pedestal, and the first original setting station 1
The first document placement station 1 is reciprocated integrally between an irradiation standby position P (position indicated by a solid line in FIG. 4) and an irradiation end position Q (position indicated by a dashed line in the figure) of the first document placement station 1 to scan the document.

At this time, the second mirror 13 reciprocates in the same direction as the first mirror 12 at a suitable speed, for example, 1/2 the speed of the first mirror 12, in synchronization with the first mirror 12.

This keeps the optical path length from the first mirror 12 to the lens 11 constant.

The light source 9, the reflection device 10, and the first mirror 12 move to a position R shown by a two-dot chain line in FIG. 4 during irradiation at the second document placement station 4.

At this time, the second mirror 13 also moves to position R'.

When scanning a book document at the first document station 1, a light source 9, a reflection device 10, a first mirror 12, a second
The mirror 13 is reciprocated and the original is fixed, but the second
When scanning a sheet original at the original setting station 4, the light source 9 and the like are fixed at positions R and R', and the original is scanned and moved by a pair of feed rollers 6.

The document sent out by the pair of document feed rollers 6 receives light irradiation while passing over the second contact glass 27 which is irradiated with light from the light source 9 at the R position.
8 onto the contact glass 2.

The reflected light projected onto the original on the contact glass 2 or the second contact glass 27 is irradiated onto the photosensitive drum 7 by the optical device 8 to form a latent image.

As for the exposure position of the photosensitive drum 7, in order to make the device as compact as possible and eliminate wasted space, the principal ray 8a of the optical device 8 and the line connecting the exposure position and the center of the photosensitive drum 7 are not aligned, as shown in the figure. It can also be tilted by an angle θ.

In this case, in order to avoid distortion of the image on the photosensitive drum 7, it is preferable to tilt the optical axis 11a of the lens 11 by an angle θ with respect to the direction 8b of the principal ray of the incident optical path of the optical device 8.

Since the second contact glass 27 is heated due to the irradiation by the stationary light source, it is cooled by the blower 29.

The copying magnification is usually 1:1 relative to the original, but if reduction is required, the positions of the lens, third mirror 15, and fourth mirror 16 are changed, and the optical path length between the lens 11 and the original and the lens 11 are changed. The ratio between the optical path length and the exposure position 14 of the photosensitive drum 7 is changed.

Note that reduction is usually required for sheet originals, and since a copy of a book original can be used as a sheet original, it would be appropriate to have a structure that allows magnification conversion for sheet originals.

In FIGS. 5 and 6, a lens IN [is fixed to a lens stand 31 attached to a lens bracket 30.

The second lens bracket 30 is connected to the optical axis 11 of the lens by a guide rod 33 attached to the second lens bracket 32.
It is movable in a direction perpendicular to a.

The second lens bracket 32 is slidably guided in parallel to the chief ray 8a by an X-direction guide rod 35 fixed to the machine frame.
In addition, the second lens bracket 32 is prevented from falling over by the rollers 36 that move on the guide 34.

The first lens bracket 30 carrying the lens 11 moves together with the second lens bracket 32 in a direction parallel to the principal ray 8b, and at the same time, the first lens bracket 30 can move independently in a direction perpendicular to the optical axis 11a.

The second lens bracket 32 holds a nut 38 that is screwed onto a feed screw 37 rotatably supported by the machine frame 3, and is moved together with the nut 38 in the axial direction of the feed screw 37 as the feed screw 37 rotates.

The nut 38 is held by the second lens bracket 32 so that it can move freely in the radial direction, taking into account the deflection and misalignment of the feed screw 37, but cannot move in the axial direction, thereby maintaining the precision of feed.

A belt pulley 39 is attached to the feed screw 37, and the belt pulley 39 is transmission connected to a belt pulley 41 attached to a drive motor 40 and a belt 42.

When the feed screw 37 is rotated in the forward and reverse directions by the operation of the drive motor 40, the second lens bracket 32 is moved in the forward and reverse directions.

A feed screw 37 acts as a drive for the movement of the lens.

The mirror bracket 43 to which the third mirror 15 and the fourth mirror 16 are attached is slidably guided by a mirror guide rod 44 fixed to the machine frame 3 in a direction that is at a certain angle to the moving direction of the lens 11, and is formed on the machine frame 3. mirror guide 45
The mirror bracket 43 is prevented from tilting by the rollers 46 moving above.

The moving direction of the mirror bracket 43 is set so that the incident position on the photosensitive drum 7 does not change even if the mirror moves.
Most standardly, it is set in a direction parallel to the bisector of the angle formed by the principal ray 8b of the light passing through the lens 11 and the principal ray 8a projected onto the photosensitive drum 7.

When converting the magnification, as explained in the principle, a certain relationship must be maintained between the amount of movement of the lens 11 and the amount of movement of the mirrors 31 and 32.

In this example, the cam device 47 maintains this relationship.

The amount of movement of the lens 11 is converted into a rotation angle by the cam device 47, and the amount of movement of the mirrors 31 and 32 is determined according to the rotation angle.

The cam device 47 includes a cam plate 49 rotatably supported on the machine frame 3 by a support shaft 48, a driving roller 50 attached to the second lens bracket 32, and a driven roller 51 attached to the mirror bracket 43.

The driving roller 50 is in contact with the first cam surface 49a of the cam plate 49, and the driven roller 51 is in contact with the second cam surface 49b of the cam plate 49.

The cam surface can also be a grooved cam.

The first cam surface 49a is formed, for example, in a straight line, and the lens 11
That is, as the second lens bracket 32 moves, the cam plate 49 rotates in proportion to the amount of movement of the lens, which is understood as a rotation angle.

The first cam surface 49 may be modified as needed without being limited to this shape.
The shape of a can be determined.

According to the rotation angle of the cam plate 49, the driven roller 51 moves in the axial direction of the mirror guide rod 44 along the second cam surface 49b.

That is, the mirror bracket 43 and the mirrors 15 and 16 move along the mirror guide rod 44 together with the driven roller 51.

By selecting the shapes of the first cam surface 49a and the second cam surface 49b, the relationship between the movement of the lens 11 and the movement of the mirror 15, 16 can be maintained in a preset relationship.

In order to ensure that the mirror bracket 43 follows the movement of the cam plate 49, the driven roller 51 is moved against the second cam surface 4 by the spring 52.
9b is pressed.

A mirror moving device is formed by the driven roller 51 attached to the mirror bracket 43, the spring 52, and the mirror guide rod 44.

The spring 52 is not limited to the position shown in the figure, but may be placed anywhere as long as the driven roller 51 and the second cam surface 49a are held in pressure contact.

The lens bracket 30 carrying the lens 11 is movably connected to the guide rod 33 with respect to the second lens bracket 32 so that the lens 11 can move in the direction of the principal ray 8b and at the same time in a direction perpendicular to the optical axis. Supported by

The lens bracket 30 has a guide roller 54 and a pressure roller 55 arranged to sandwich a guide 53 fixed to the second lens bracket 32 so as not to tilt.

As shown in the above principle, a lens guide cam device 56 is provided to move the lens 11 in a direction perpendicular to the optical axis in a predetermined relationship with respect to the amount of movement in the direction of the principal ray 8b.

The cam device 56 has a cam plate 57 fixed to the machine frame 3 and a cam follower roller 58 attached to the first lunz bracket 30.

A cam groove 59 is formed in the cam plate 57 and has a shape according to a relational expression of the amount of movement of the lens in the X direction and the Y direction.

When the lens bracket 30, that is, the lens 11 moves in the direction of the principal ray
As a result, the lens bracket 30, that is, the lens 11 moves in the Y direction.

With this structure, when the lens 11 moves in the X direction, the lens 11 automatically moves in the Y direction in accordance with the movement, and the third mirror 15 and fourth mirror 16 also move in a predetermined relationship.

If the copying magnification to be converted is selected in advance, the lenses and mirrors can be automatically stopped at positions corresponding to the selected magnification.

That is, a switch actuating member 60 is attached to the second lens bracket 32, and a switch, such as a microswitch 61, is attached to the machine frame 3 so that the actuating member 60 is activated when the lens reaches a position corresponding to a preselected magnification.

When performing two or more types of magnification conversion, two or more switches 61 are provided.

When a magnification is specified using a button or the like provided on the control panel of the copying machine, when the operating member 60 operates the switch 61 corresponding to the magnification, the drive motor 40 is stopped and the lens is positioned.

When using two or more copy magnifications, use the switch actuating member 60.
moves past the switch 61, and the direction in which the switch 61 is actuated is not limited to one direction.

A positional shift may occur between when the switch actuating member 60 operates the switch 61 by moving it from the right side of the figure and when it operates it by moving it from the left side.

To avoid this, as shown in FIG. 7, an actuating piece 65 is used as the switch actuating member 60, which is rotatably supported by a pin 62 and has an elongated hole 64 that engages with a fixing pin 63.

The rotation angle of the actuating piece 65 is limited by the elongated hole 64.

If the position where the rotation angle of the actuating piece 65 is limited by the elongated hole 64 is exactly the position that activates the contact of the switch 61, then when approaching the contact from the right side, the switch 6 will be in the position shown by the solid line.
When the vehicle approaches from the left side, the contact point of switch 61 is activated at the position shown by the chain line.

Although the position of the actuating piece changes, the position of the pin 62 that supports the actuating piece remains constant in both cases.

That is, the second lens bracket 30 can always actuate the switch at a constant position no matter which direction it approaches the switch 61.

In addition to the methods described above, lens positioning can be done by using a pulse motor as the drive motor and regulating the amount of motor rotation by the number of pulses, or by using a servo motor and its related position detection device and designation device. etc., may be used as appropriate.

Further, by appropriately selecting the lens positioning device and the document scanning speed change position, stepless variable magnification copying is also possible.

The device shown in FIGS. 5 and 6 makes it possible to change the copying magnification by using a simple device that moves the lens and mirror while the subject position, that is, the document surface, and the imaging surface, that is, the exposure position of the photosensitive drum are fixed. Moreover, this can be done automatically, and the operation has become easier because the document can be positioned by simply aligning the edge with the reference position, regardless of the magnification, while changing the magnification.

With this device, book originals can be copied normally, and it also includes a light source, a reflection device, and a first . If the second mirror can be moved beyond the scanning stroke to the second document placement station by the same drive device used for reciprocating scanning, and can be fixedly held at that position, then the same optical device can handle documents in two different positions. Switching copying by irradiation is possible.

This switchable copying feature allows the copying positions of book originals and sheet originals to be separated, and since sheet originals can be copied while being fed by a pair of feed rollers, the copy length is not limited and it is possible to easily copy very long sheet originals. Copying is also possible.

When converting the copying magnification of an original, it is necessary to automatically change the original scanning speed, that is, the original feeding speed or the irradiation device movement speed according to the magnification.

This is because the photosensitive drum rotates at a constant speed.

Of course, the original speed may be kept constant and the speed of the photosensitive drum may be varied.

By making it possible to change the speed of the photosensitive drum l according to the magnification, it is possible to copy a hook original at the first original setting station and a sheet original at the second original setting station while keeping the original scanning speed constant. It is also possible to change the copy magnification.

Although the figure shows an example in which copy paper of a fixed size is fed, it is also possible to feed roll paper.

According to the present invention, a copying device with a simple structure, easy operation, and variable magnification has been obtained.

[Brief explanation of the drawing]

Figures 1 and 2 are principle diagrams showing the relationship between the subject position, lens, and imaging plane during magnification conversion. Figure 1 shows the principal ray when it coincides with the optical axis, and Figure 2 shows the principal ray Figure 3 is a plan view of Figure 1 or 2, where is tilted to the optical axis.
FIG. 4 is a cross-sectional explanatory diagram of a copying machine using the optical device according to the present invention, FIG. 5 is a partial cross-sectional view of a magnification conversion device that moves lenses and mirrors, and FIG. 7
The figure is an explanatory view of the switch actuating member. 2.27...Document support device (contact glass), 6...Document feed roller pair, 7...
Photosensitive drum, 9...Light source, 10...Reflector, 11...Lens, 15...Third mirror, 16...Third mirror 4 mirrors, 30...
...Second lens bracket, 32...Second lens bracket, 37...Feed screw, 38...
... Nut, 40... Drive motor, 47...
...Cam device, 49...Cam plate, 50...
...Main roller, 51...Dolive roller, 56.
... Lens guide cam device, 57 ... Cam plate, 58 --- Cam follower roller, 60 ...
...Switch operating member, 61...Micro switch.

Claims (1)

[Scope of utility model registration request] A copying apparatus that includes a document support device, a document irradiation device, a photoreceptor that forms an image of the document, a lens that focuses the image of the document onto the photoreceptor, and a mirror that reflects light emitted from the lens onto the photoreceptor. A drive device for moving the lens in the direction of the principal ray, a cam device that rotates following the linear movement of the lens in the direction of the principal ray and whose rotation angle is determined according to the amount of movement of the lens, and the cam device of the cam device. A mirror moving device that linearly moves the mirror back and forth following the rotational movement, a device that stops the drive device when the amount of lens movement corresponding to the required magnification is reached, and a device that adjusts the original scanning speed and photoreceptor according to the copying magnification. a device for changing at least one of the speeds, the cam device abutting a portion of a lens bracket substantially integral with the lens to determine the rotation angle according to the amount of movement of the lens;
A variable magnification copying apparatus comprising a second cam surface that determines the amount of movement of the mirror moving device according to the cam surface and its rotation angle.